Among those charged are two officers of Russia's Federal Security Service, and two hackers who allegedly worked together to crack 500 million Yahoo user accounts.

It has long been known that the Kremlin employs criminal hackers for its “geostrategic purposes” as it offers deniability to Moscow and freedom from legal troubles for the hackers.

A US intelligence official told Reuters that employing criminal hackers helps "complement Kremlin intentions and provide plausible deniability for the Russian state".

To be fair the United States sometimes engages with criminal hackers as well, buying tools from them or recruiting them to help find other criminal hackers, cyber security professionals.

Milan Patel, a former FBI cyber agent and now managing director for cyber defense at K2 Intelligence, said the intermingling of espionage and cybercrime in Russia had led the United States and its allies to be far warier about alerting Moscow to criminal hackers.

If they did, then the guys would disappear off the battlefield and end up working for the Russian government, Patel said.

Russian news accounts stressed that one of the FSB agents, Dmitry Dokuchaev, was arrested by Russian authorities in December and charged with treason.

The indictment charges Dokuchaev with having acted as a handler for a hacker named Karim Baratov, directing him to use the Yahoo data to crack emails on other systems and paying him a bounty when he succeeded.

Baratov is in custody in Canada, according to the Toronto police, while Dokuchaev remains in Russia.

Senator John Warner of Virginia, the ranking Democrat on the Senate Select Committee on Intelligence, said in a statement the indictments showed "the close and mutually beneficial ties between the cyber underworld and Russia’s government and security services".

He said the case "underscores the complexity and the urgency" of the committee's investigation of Russian interference in the US election.